how to background to specific object in html css code example

Example: background in css

/* There are several ways of setting a background, like in HTML or CSS
	(I advise you to set it in CSS) You can set a colour or image with
	the same attribute: */

/* Setting the colour in a div, body, html (html is the whole page),
	class, and id: */
div, body, html, .myClass, #myId {
	background-color: grey;
}
/* Setting the image: */
div {
	background: url("img.jpg");
}
/* If you want to call an image from a specific directory use a '/'.
	For example, the image is in a folder called 'Images' (the HTML
	and CSS files have to be in the same folder as the 'Images folder') */
div {
	background: url("Images/img.jpg");
}